Comment 1 for bug 1854151

More rationale from CLHS 22.3.3.2:

If all of w, d, and e are omitted, then the effect is to print the value using ordinary free-format exponential-notation output; prin1 uses a similar format for any non-zero number whose magnitude is less than 10^-3 or greater than or equal to 10^7. The only difference is that the ~E directive always prints a plus or minus sign in front of the exponent, while prin1 omits the plus sign if the exponent is non-negative.